President Donald Trump drew the ire of professional athletes for comments he made at a rally in Alabama on Friday night and on Twitter on Saturday morning.

Trump first took aim at the NFL, saying team owners should fire players for taking a knee during the national anthem.

The President said owners should respond to players by saying, "Get that son of a bitch off the field right now, he's fired. He's fired!"

He doubled down on the comments on Saturday afternoon.

If a player wants the privilege of making millions of dollars in the NFL,or other leagues, he or she should not be allowed to disrespect....

— Donald J. Trump (@realDonaldTrump) September 23, 2017

...our Great American Flag (or Country) and should stand for the National Anthem. If not, YOU'RE FIRED. Find something else to do!

— Donald J. Trump (@realDonaldTrump) September 23, 2017

Last year, Colin Kaepernick -- formerly with the San Francisco 49ers, but currently without a team -- drew national attention for refusing to stand during "The Star-Spangled Banner" prior to kickoff."I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color," Kaepernick told NFL Media in August 2016. Trump also singled out the NBA's Golden State Warriors player Stephen Curry.Curry said on Friday that he didn't want to take part in the traditional White House visit that league champions make.Trump responded on Saturday morning, tweeting, "Going to the White House is considered a great honor for a championship team. Stephen Curry is hesitating, therefore invitation is withdrawn!"NBA star LeBron James was among the first professional athletes to respond to the President's comments. "Going to White House was a great honor until you showed up!" he wrote.

U bum @StephenCurry30 already said he ain't going! So therefore ain't no invite. Going to White House was a great honor until you showed up!

— LeBron James (@KingJames) September 23, 2017

The Houston Rockets' Chris Paul questioned the President's priorities -- suggesting he had other things to worry about.

With everything that's going on in our country, why are YOU focused on who's kneeling and visiting the White House???

— Chris Paul (@CP3) September 23, 2017

And I doubt he's man enough to call any of those players a son of a bitch to their face...

How you gonna withdraw an invite that somebody already said they weren't attending ?

— Bradley Beal (@RealDealBeal23) September 23, 2017

Other athletes shared the belief that many others were expressing online -- that Trump was targeting black athletes."Unbelievable what he just said," football player Cecil Shorts wrote of Trump's comments in Alabama. Shorts pointed to a tweet from author and activist Shaun King, who had raised the race issue.

Unbelievable what he just said !!

— Cecil Shorts III (@CecilShortsIII) September 23, 2017

Here's what other athletes had to say:

Only validates @Kaepernick7 bringing social injustice to light, he kneeled hoping it'd bring attention to what he believed in... Has it not?

— cameron jordan (@camjordan94) September 23, 2017

The behavior of the President is unacceptable and needs to be addressed. If you do not Condemn this divisive Rhetoric you are Condoning it!!

— Richard Sherman (@RSherman_25) September 23, 2017

Continue to use your voices and your platforms for racial equality and to stop injustices in our communities. This is bigger than us!!!

— Michael Thomas (@Michael31Thomas) September 23, 2017

It is a sad day when the #POTUS seeks to disregard and punish American citizens for peacefully exercising their constitutional rights.

— Benjamin Watson (@BenjaminSWatson) September 23, 2017

What an emphatic response, where was this passion in response to Charlottesville...

— Max Garcia (@MGarcia_76) September 23, 2017

"Stick to sports boy... Sit down and do what your told. Say or do something we don't like and your fired" Well I hate to break it to ya...

— Chris Conley (@_flight17_) September 23, 2017

When will people learn that fear won't make someone sit down. It quite possibly will make more stand up for what they believe in.